Propeller.



S. HEATH.

PROPELLER.

APPLICATION FILED DEC. 26, 1911.

Patented Dec. 16, 1913.

2 SHEETSSHEET l.

S. HEATH.

PROPELLER.

APPLICATION FILED 1730.26, 1911.

Patented Dec. 16, 1913.

2 SHEBTS-SHEET 2.

' a err ear care recreates.

Specification of Letters Patent.

Patented Dec. 16, 1913.

Application filed December 26, 1911. Serial No. 667,657.

To all whom it may concern:

Be it known that I, SPENCER HEATH, a citizen of the United States, residing at Washington, in the District of Columbia, have invented new and useful Improvements in Propellers, of which the following is a specification.

This invention relates to screw propellers and particularly to screw propellers for aeronautical use and has for its object such modes and details of construction as will afford the greatest economies of labor and material, together with improved strength, durability and uniformity in the opposing blades.

With these objects in view and further objects which will appear from the nature of my improvements, 1 have invented the improvements illustrated .by the accompanying drawings forming a part of this specification, and in which drawings,

Figure 1 is a top plan View of a propeller, Fig. 2 is a bottom plan view, Figs. 3, 1, 5, and 6, are sections on line 3-3, 14:, 55 and 66 respectively of Figs. 1 and 2. Figs. 7 and 8 are part plan views of separate laminations, Fig. 9 is a plan view of Figs. 7 and 8 assembled, Fig. 10 is an elevation of Fig. 9, Fig. 11 is a diagram of transverse" sections, Fig. 12 is an end view of a propeller, Fig. 13 is a perspective of a twisted lamination.

in the drawings corresponding reference numerals refer to corresponding parts.

Referring to Figs. 1 and 2, each blade of the propeller is formed of a series of spe- ....cially formed laminations 1, 2, 3 and 4:, the

v the blade.

contour of these laminations being such that when the faces of the blades are reduced to a regular surface the desired form will be developedwithout removing additional material.

From the beginning of the construction of wooden propellers it has been more or less of a problem to secure sufficient transverse strength in the wood near the ends of Various expedient's have been adopted for this purpose; perhaps the simplest being to size or impregnate the wood with glue. A further expedient quite frequently employed is to swathe the blades with linen, canvas or like fabric, laid on with glue. The present improvement consists in placing transverse reinforcing inserts through the bladm. Ail 1 the ends of the blades this insert is most conveniently anfrom the ends of the blades it is found eX- pedient to bore holes in an edgewise direction into or through the blade, securing in these holes with glue transverse dowels 8, 9 and 10, along the lines l4, 55 and 6'6, as shown in Figs. 1 and 2, and also in the sectional views, 3, 4, and 5. This combination of reinforcing the parts provided by veneer 1n the thin portion of the blade at the end, and by the transverse dowels crossing the blade at various distances from the end, so binds the material of the blade in a transverse direction that extraordinary strength againstsplitting is secured, and in case of accident damaging the end of the blade the injury is more frequently local to the end without extending far into the blade and destroying it beyond repair.

As a further means for increasing the strength of the propeller in transverse directions, I employ inlaid veneers, 11, 12, 13, (Figs. 1 and 2) and 15, 16, 17. 18 (Figs. 7 and 10), set into the surface of the laminations before the laminations are assembled and glued. In Fig. 7, 15 and 16 represent diagonal reinforces inlaid in the surface-of the laminations where they come together at the hub portion. Fig. 8 shows another lamination similarly reinforced by the diagonal inlays 17 and 18, in Figs. 9 and 10. Fig. 7 is superposed upon Fig. 8 in the relative positions they occupy in the assembled propeller.

In assembling the laminations when they are placed in the portion forming the hub provision is made that the reinforces in one lamination shall be in a diagonal position with respect to the reinforces in the adjacent lamination or on the opposite side of the same lamination. This reinforcing means as shown in Figs. 7 to 10, is especially valuable for increasing the strength of the wood in the hub, and particularly when it is necessary to remove a large amount of material at the center of the hub to receive the shaft or sleeve upon which it revolves. This diagonal reinforcing, however, need not be confined to the region of and adjacent the hub, but is advantageously employed between the laminations in other parts ofthc blades, as shown by 11, 12 and 13, Figs. 1 and 2.

Apart from the extraordinary strength secured by the above construction it has been found desirable to select the wood, forming corresponding portions of each blade in such manner that the radial fibers, which are especially conspicuous in oak wood, shall run in a direction transverse to the blade. In order to accomplish this lt' iS necessary that the laminations in each blade originate at or near the center of the propeller extending oppositely toward the tips, thus making the laminations separately for each blade. By this means it is possible to obtain the same direction and similarity of grain in the wood in corresponding portions of the opposite blades. In making the joints between the laminations at the center of the propeller I have found it desirable and economical of material to form the opposing laminations in exact duplicate and securing each pair of them together by a diagonal "joint as shown at 20 and 21 in Figs. 7 and 8. This joint extends in a diagonal direction, preferably through the center of the hub, but it may be adjacent the hub or in any part of the propeller more or less removed therefrom, the plane of the joint being substantially parallel with the axis of the hub. Fig. 8 shows how the diagonal joints run in opposite directions, the joint 20 running in an opposite direction from the joint 21 as clearly shown in Fig. 9. The purpose of this is that when the two pairs of joined laminations are superposed in the propeller, the joint of each pair of laminations shall be at a decided angle to the joint of the next adjacent pair, since this reversal of the joints causes the laminations in the opposing blades to overlap each other, thereby securing the blades together more perfectly at the central portion. From Fig. 9-, it is seen that the lamination 25 in one blade overlaps the lamination 22 in the opposing blade and that 24 overlaps 23. By means of this overlapping the two blades are firmly joined at the center. It is not necessary, however, that all the laminations of the propeller be joined at the center or that the same form of joint be employed in all. In some cases I prefer to use the diagonal joint shown, for the interior laminations, using either an integral lamination without any joint for one or both of the exterior laminations, or using for these laminations the form of joint illustrated in my Patent No. 1,006,209. Further economy in the employment of material. I accomplish by means of giving to the laminations of each blade a Wind or twist so that the top and bottom surfaces of each lamination are formed or distorted out of a true plane, as

clearly shown'in Figs. 11, 12 and 13. By

giving the laminations a wind as shown, it becomes possible to increase or diminish the angularity of the blades from what the angularity would be with the laminations remaining in the plane form. In order to obtain a very high pitch or angularity together with considerable width of blade it is necessary to use a suflicient number of laminations to build up the entire propeller to a height represented by -the tangent X of the blade angle Y in Fig. 11. By means of forming'or distorting the laminations as shown in Fig. 13 it is possible to obtain a high pitch and blade angle represented in Fig. 10 by the angle Y with the greater height of blade represented by the line X.

In this way a higher angle and pitch is obtained without increasing the number or thickness of lamination required. In a similar manner by giving the laminations a contrary wind the angle and pitch ofthe blade can be greatly reduced, as shown by Y and X The end view, Fig. 12, shows in full lines the form of the blade with the laminations distorted to the angle y, Fig. 11. The dotted line shows the same blade of less pitch with the laminations normal or flat. It is thus apparent that by formin or distorting the laminations it is possi le with laminations of the same design to produce a propeller having a very high pitch or a very low pitch as desired. By raising the pitch in this manner a blade of great pitch and width can be produced by a small number of laminations having a much less aggregate thickness than would be otherwise required.

With plane laminations their surfaces lie uniformly in a plane normal to the propeller axis. By giving them a wind in either direction this .angle is increased or diminished as desired, the amount of change in this angle, of course, being greatest in, parts remote from the hub. To give the laminations the special twisted form which I have indicated they may be eithencurvedby cg ving them in this manner or forcibly dis- I torted either before or during the process of gluing them together to form the propeller, using steam or any other necessary means for making the wood sufiiciently. pliant.

Having now described my invention what I claim is:

1. A propeller built of multiple laminations assembled in step formation, the laminations being distorted with a wind out of a plane normal to the propeller axis.

2. A propeller built up of multiple laminations assembled in step formation, the laminations being distorted to diminish the pitch of the propeller.

3. A propeller built up of multiple laminations assembled in step formation, the

laminations being distorted to diminish the pitch of the propeller.

4.- A propeller built up of multiple laminations assembled in step formation, the laminations being formed with a Wind out ofa'trueplanemormal to the propeller axis.

5. A propeller having its blades reinforced by veneer inserted in the blades substantially parallel to the front and back faces thereof.

6. A propeller" having its blades reinforced by transverse veneer inserted in the blades substantially parallel to the front and back faces thereof.

7. A propeller having its blades reinforced by. veneer inserted in the ends of the blades substantially parallel to the front and back faces thereof.

8. A propeller having its blades reinforced by transverse veneer inserted in the ends of the blades substantially parallel to the front and back faces thereof.

9. Apropeller having its blades reinforced by dowels inserted in a transverse manner in the general direction of the width of the blade. j

10. In'a laminated propeller corresponding laminations separately formed for the opposing blades and secured together by a diagonal joint at the hub of the propeller, the contacting surfaces of said joint being substantially parallel with the axis of the hub and diagonal veneers inlaid across said joint.

11. In a laminated propeller, corresponding laminations for the opposing blades separately formed and joined atthe center by a diagonal joint, the diagonal joints of each set of laminations being diagonal in the opposite direction from the joint of the next adjacent laminations.

12. In a laminated propeller, laminations separately formed for the opposing blades and secured together by a joint, and reinforcing veneers inlaid in the laminations transversely across said joint.

13. In a laminated propeller, corresponding laminations for the opposing blades separately formed and joined at the center by a diagonal joint, the diagonal joints of each set of laminations being diagonal in the opposite direction from the joint of the next adjacent laminations, and reinforcing veneers inlaid transversely across said joints.

14. A propeller having laminations through its hub portion and diagonal reinforcing veneers inlaid in said laminations, the veneers in each lamination being diagonal to the veneers in the adjacent lamination.

nations assembled in step formation, a portion of the pitch of the propeller being produced by the slant of the step formation and the remainder of the pitch being produced by a twisted formation of the several laminations.

16. A propeller built up of multiple laminations assembled in step formation, the pitch of the propeller being diminished below the pitch resulting from the slant of the step formation by a twisted formation of the several laminations.

SPENCER HEATH.

Witnesses:

E. M. CoLFoRo, OSCAR PAYNE.

' 15. A propeller built up of multiple lami- 

